Tools

IoT battery life calculator

Estimate how many months a battery-powered IoT device lasts from its duty cycle: the sleep current, the current and duration of each active burst, how many times a day it wakes, and the battery capacity. The figures are indicative — they don't include real self-discharge, temperature or retransmissions — but they let you compare designs and size the battery. Everything is computed in your browser.

Estimated life

14.2months

1.19 years · 434 days

Duty cycle

0.222%

Average current: 277 µA

Daily consumption split

Active bursts: 96.4% · Sleep: 3.6%

Daily draw: 6.639 mAh · Usable capacity (after derating): 2880 mAh

Indicative estimate: it doesn't include self-discharge, temperature effects, voltage sag under current peaks, or retransmissions from poor coverage.

How the life is estimated

A battery-powered IoT device spends almost all its time in deep sleep drawing microamps, and wakes for a moment to measure and transmit drawing milliamps. The life is essentially the battery's usable capacity divided by the average daily draw. That average is almost always dominated by the sleep current, because however small it is, it runs 24 hours a day — which is why dropping from 10 to 2 µA in sleep usually extends life more than optimizing the active burst. The burst matters when the device transmits often or is slow to attach: every second of radio-on at 120 mA costs the same as hours of sleep. We also apply a configurable capacity derating, because a battery never delivers 100% of its nominal capacity: self-discharge, the low-voltage cutoff and cold eat a share. Change the values to see which lever — sleep, sending frequency or burst size — extends your design most.

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Frequently asked questions

What drains more battery in an IoT device, sleep or transmission?
It depends on the duty cycle, but for most sensors that wake a few times a day the sleep current dominates: even at microamps, it runs 24 hours a day. On devices that transmit frequently or are slow to register on the network, the active burst becomes dominant. The calculator splits the consumption between the two so you can see which is your case.
Why apply a derating to the battery capacity?
Because the nominal capacity printed on the battery (say 3600 mAh) is almost never fully available. Self-discharge, the device cutting off when voltage drops below a threshold, and temperature effects reduce the truly usable energy. A 15–30% derating is a prudent assumption in many designs; tune it to your battery chemistry and temperature range.
Does it work for NB-IoT and LTE-M?
Yes, the model is agnostic to the radio technology: it only needs the current and duration of the active burst, which on NB-IoT and LTE-M are usually lower thanks to the PSM and eDRX power-saving modes. If you use PSM, the sleep current you enter should be the power-saving-mode current, not that of a fully active modem.
Are the figures exact?
No — they're indicative and deliberately conservative in structure. They don't model each chemistry's real self-discharge, voltage sag under current peaks, cold, or retransmissions from poor coverage. Use them to compare designs and size the battery; for a field figure, measure the device's real consumption over several cycles.

Designing a battery-powered device?

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